Universal adjustable pitch marine propellers



June 14, 1966 H. J. NICHOLS 3,255,827

UNIVERSAL ADJUSTABLE PITCH MARINE PROPELLERS Filed Oct. 50, 1964 2 Sheets-Sheet 1 INVENTO HA RRYJ. NIG HOL June 14, 1966 Y H. J. NICHOLS 3,255,827

UNIVERSAL ADJUSTABLE PITCH MARINE PROPELLERS Filed Oct. 50. 1964 2 Sheets-Sheet 2 INVENTOR.

I 1 FE l HARRY J.N|CHOL5 United States Patent 3,255,827 UNIVERSAL ADJUSTABLE PITCH MARINE PROPELLERS Harry J. Nichols, 356 Briar Road, Point Pleasant, NJ. Filed Oct. 30, 1964, Ser. No. 407,928 13 Claims. (Cl. 170-173) This invention relates to improvements in adjustable pitch marine propellers and more particularly to an improved form of propeller blade for liquids, termed a hyperconic propeller blade, which is particularly adapted for such propellers with adjustable blades.

The prior art describes various forms of propellers and propeller blades for marine propulsion, but in recent times the trend has been towards monolithic cast propellers having three, four or five helical radial blades. The form of the blades for such sophisticated" propellers, that is the blade sections, outlines and surfaces, have become exceedingly complex, so that elaborate theoretical computations and hundreds of dimensions are required to specify the particulars of a single propeller, which propeller is supposed to be most efficient for a particular vessel. In casting large one-piece propellers, a large amount of excess metal is cast to obtain a sound casting and to allow for warping and distortion of the casting when it cools. Hence, a large percentage of the metal in the propeller as cast must be removed to bring it to precise form and dimensions, and this metal is mainly removed by chipping, grinding and filing by hand labor. For example, a recent large tanker propeller was made from a one-piece bronze casting weighing 114,500 pounds which yielded a propeller having a finished weight of 82,725 pounds; hence almost 32,000 pounds of metal, representing 28% of the casting weight, had to be removed during finishing, thereby obviously raising production costs. Moreover, the high cost of such sophisticated monolithic propellers has not yielded any offsetting gain in propulsion efficiency, hence they are not ideal from the standpoint of economy or efiiciency.

Costly attempts have been made to develop special milling machines to enable the surfaces of marine propeller blades to be precisely machined, thereby to reduce hand labor; but such attempts have not proved economical because of the wide variety of propellers and blade forms. Also, the helical blades of a fixed pitch propeller require a highly complicated movement of the cutter while the surfaces are being machined which greatly increases the overall costs. Consequently, few marine propellers have machined surfaces, therefore require costly hand work.

Adjustable pitch propellers constructed according to this invention can therefore provide substantial advantages over fixed-pitch propellers by reducing scrap and hand labor, by enabling the pitch of the propeller to be adjusted to improve propulsion performance, to reduce over-all costs by reduction of numbers of models, better standardization, reduced material, labor and shipping costs, and easier and less costly repairs and blade replacements.

It is therefore the main object of the present invention to overcome various limitations and drawbacks of the prior art referred to above; and to provide a complete,

improved adjustable pitch propeller and a novel improved blade form for such propellers; all characterized by utmost simplicity, practicality, versatility and low cost of manufacture and distribution.

A further object is to provide an adjustable pitch propeller whose blades can readily be locked in any desired precise angular position, yet can be readily unlocked and justment of the pitch is required.

3355,82? Patented June 14, 1966 Another object is to provide an adjustable pitch propeller whose blades can be individually and readily removed and repaired or replaced in event of damage. Another object is to provide an adjustable pitch propeller which can be easily and quickly mounted on its shaft, and quickly coupled and uncoupled by special built-in means provided by the novel propeller construction. Another object is to provide an adjustable pitch propeller having special keyless coupling means, thus eliminating the need for a conventional key to permit slipping of the hub on the shaft.

Another object is to provide a novel and improved blade form having the simplest feasible geometric shape and surfaces which are inherently smooth and even; and whose back and face surfaces can be readily, economically and precisely machined on ordinary rotary machine tools; such as lathes, boring mills, and the like. Moreover, the back and face surfaces can be machine generated in a simple manner, thus providing smooth perfectly faired surfaces of unusual precision.

Another object is to provide a blade form of feasible minimum thickness which can economically utilize forged or pressed metals, as well as castings, of superior strength and corrosion resistance such as Monel, stainless steel, etc. Yet another object is to provide a marine propeller blade which is highly versatile in application and which can be serially standardized in the whole gamut of size ranges; that is pro ellers adapted to all sizes of vessels from inboard motorboats to giant tankers.

With these and other objects in view, as well as other advantages provided by the improved construction, the invention consists in various novel features and combinations thereof set forth in the claims with the understanding that the several necessary elements constituting the same may be varied in proportion and some details without departing from the nature and scope of the invention as defined in the appended claims. I

To enable others skilled in the art to comprehend the underlying features of this invention so that they may embody the same by suitable modifications to meet various practical applications and modifications contemplated by the invention, drawings showing preferred embodiments of the invention form part of this disclosure, in which:

FIG. I shows a longitudinal view in half-section of a typical propeller assembly according to the invention.

FIG. II shows an abbreviated left end view of the same assembly as seen from the outboard end of the propeller.

FIG. III shows a typical separable blade according to the invention in conventional developed outline and radial section with successive transverse sections indicated by boundary lines.

FIGS. 1V and V show in plan view and mid axial section respectively a schematic diagram illustrating a typical machine set-up for turning the back surface of hyperconic blades.

FIGS. VI and VII show a similar schematic diagram illustrating a typical machine set-up for turning the driving face surface of hyperconic blades.

Referring to FIGS. I and II, which show a typical example of the main invention, the unitary propeller assembly comprises generally a one-piece streamlined hub 1, having an axial tapered bore 1b and plural equally spaced radial blind blade sockets 1s, fastened tightly but demountably on the tapered end of a propeller shaft 10; propeller blades 2 each having at the hub end a circular flange or boss 2b mounted in a blade socket so that they can be turned each about its own axis forpurposes of adjusting the pitch angle of the blades; and special blade mounting means in each blade socket for securing and locking each blade in the set angular position at adjustment; thus enabling quick and easy subsequent readjustment, or removal and replacement of any individual blade if required.

The blades 2 are each provided with a circular boss 2b mounted turnably in their mating sockets, including a short cylindrical center pilot 20 for facilitating machining and accurately centering the blades. The bosses 2b are each detachably mounted in a blade socket by means of a demountable circular blade anchor disc 3, of substantially the same diameter as the blade socket and blade boss; and circularly arranged and spaced multiple blade securing cap screws 4 which also function as lock screws. These screws have wrenchable heads seated in recesses in each blade boss and threaded shanks extending through plain holes in boss 2b into mating-threaded through holes in the associated anchor disc 3, as shown. The number, size and material of the lock screws 4, as well as their length, are precisely designed and specified in each case to assure an adequately strong connection of each blade to the hub of the propeller with adequate securing factors, so that the bolted connection is substantially stronger than the blades at the root section; whereby possible failure in event the propeller strikes an obstruction will occur in the blade per se. Also, the lock screws shall project at the inner ends somewhat, thereby to provide for positive locking action, as explained hereafter.

Each anchor disc 3 has a thickness suificient to provide adequate engagement with the threads of the lock screws 4, say an engagement equal to at least one diameter of the screws; and each is formed with a 45 chamfer on the outer corner; thereby to provide a conical annular bearing surface for blade securing purposes. Each anchor disc is strongly secured in its socket by special retaining and locking means comprising a special locking ring 5, preferably of plain uniform square section and made of strong hard resilient noncorrosive spring metal, say stainless steel square wire drawn to spring temper. It is also preferred that the square wire be edge-wound when coiled, whereby the faces of the locking ring present inclined thrust bearing surfaces sloping radially about the axis. Each locking ring is half-seated in a closely fitting internal 90 V-groove 5g located in the wall of the bore of the associated blade socket; and in a concentric 90 V-groove provided by the 45 chamfers on the adjacent corners of the blade boss 2b and the anchor disc 3. A small locking ring of square wire edge-coiled and wedged tightly in a fitting 90 V-groove as shown can withstand extraordinary axial thrust loads without damage to the working parts; because the axial thrust load is converted into a compressive force evenly distributed around the circumference of the locking ring and its supporting groove; thereby providing maximum effective bearing surfaces and thrust supporting capability. For example, assuming a socket bore diameter of two inches, a stainless steel locking ring having say one-tenth inch square section, and for the hub manganese bronze of 40,000 =p.s.i. axial yield strength, the allowable thrust load would exceed ten tons i.e. far in excess of any possible blade working loads and even the strength of the blade itself.

The lock screws 4 preferably extend through the threaded holes in anchor disc 3, and project slightly therefrom, so that the bolt ends engage and push forcibly against the bottom of the blind blade sockets in hub 1. Consequently, when the lock screws 4 are tightened by torque wrenching, these screws function as jack-screws which tend to jack anchor disc 3 out of the hub socket. But in each case lock ring 5 is wedged outwardly by the conical chamfer on the corner of'the anchor disc and thus locks anchor disc 3 against outward displacement, and also against turning in the blade socket. Thus, as each of the lock screws 4 is tightened an accumulative powerful axial load is applied by the anchor disc 3 to lock ring 5, which is thus wedged into its seating groove so as to fix anchor disc 3 solidly in its blade socket. Moreover, the projecting ends of lock screws 4 apply heavy local forces against the bottom of the blade socket, thus functioning as positive set screws. While the ends of lock screws 4 may be coned or cupped to augment the set screw action, it is preferable to have flat or slightly rounded ends on the lock screws; thus to facilitate successive precise adjustments of the pitch angle of each blade. In summary, each blade can be set and positively locked in any desired angular position by turning the blade when loosened to the desired angular position and wrenching tight the lock screws 4; whereby these screws and the lock ring 5 lock the blade boss rigidly and positively in its blade socket, secure against displacement even by accident.

Propeller hub 1 is preferably coupled on propeller shaft 10 by special coupling means known as the Myriad- Loc quick keyless shaft coupling described in detail in my US. Patent No. 3,143,366, issued August 4, 1964. Accordingly, shaft 10 is preferably slightly tapered at the outboard end 10t according to common practice, except that no keyway need be cut along the tapered portion. The taper of the shaft is preferably in the range of say fifty to one hundred thousandths of an inch in diameter per inch length, so that the hub can be pulled up and wedged tightly on the shaft, but can ,be later pushed off the shaft without damage. At the outer end, the shaft is preferably provided with a coaxial complementally threaded stem 10s to mate with the threaded bore of special jack-nut 6, preferably having a castellated crown.

-Hub 1 is provided as shown with a tapered axial bore complemental to the tapered portion of shaft 10 and also with a coaxial plain counterbore 1c adjacent to the small end of the tapered bore and somewhat larger in diameter than this small end: thus providing an annular abutment or shoulder at the inner end of the counterbore. A small circumferential V-groove is cut in the interior wall of the hub counterbore intermediate its ends for the purpose of seating a special uncoupling thrust ring 7 similar to lock ring 5. Jack-nut 6 preferably comprises a collar nut with a hex head adapted to be torqued by an ordinary socket wrench. Jack-nut 6 also has a round integral collar at the inner end, fitting the axial counter bore 10; the outer circular corner of the collar having a chamfer of 45 slope; thus providing a conical thrust bearing surface, as in the case of anchor disc 3. Shaft stem 10s may also have near the outer end a small diametral cross-hole adapted to receive a commercial cotter pin 8 for purposes of securing jack-nut 6 in assembled position, as shown in FIG. II.

At assembly of the hub on the shaft, a special noncorrosive lubricating lute, containing fine hard abrasive grains such as emery dust, may be applied to the mating surfaces of the tapered parts, so that when pulled together these particles become embedded in the mated parts; thus providing a myriad of microscopic keys. Thus, the normal friction of the taper mated parts may be augmented by positive locking action due to the lute, thus rigidly locking the hub on the shaft. The lute also prevents the hub sticking on the shaft.

While propeller blades of conventional section and form can be employed in conjunction with the other main elements of the present invention, a novel and unique type of propeller blade, herein termed the Hyperconic propeller blade, is preferred in order to gain maximum advantages as hereinafter disclosed. In general, the novel Hyperconic propeller blade is characterized by hyperbolic incremental blade sections and by a precise smooth blade back surface constituting a conical surface of rotary revolution which can be machine generated with utmost precision by turning the blade on a lathe or the like. As will be explained, the Hyperconic blade also tends to prevent or reduce cavitation under severe and adverse propulsion conditions which normally induce cavitation. Moreover, the Hyperconic blade is universal, that is the sam blade can be used for either a right or left turning propeller, and can be turned about its axis to provide any desired pitch angle for purposes of obtaining maximum propeller performance.

Referring now to FIG. III which shows the main fea tures of the novel Hyperconic propeller blade of the invention in conventional graphic presentation, the pre ferred outline of the basic blade shape is circular for typical high speed applications, but may have other outlines for particular applications. In the figure the left semicircle represents the front and driving face surface of the blade; the right semicircle the back surface of the blade. The median radial section of the blade preferably has a uniform radial slope or taper, whereby weight of material is conserved by progressively thinner blade sect-ions outwardly from the hub, as indicated. The face of the blade is preferably planiform, that is entirely flat or seiniflat on the outer portion, while the back surface of the blade is substantially of conical curvature, considered as a whole; therefore any blade circular section is substantially plane-convex with a hyperbolic curvature at the back.

Since any secant planar section of a right circular cone produces a hyperbola on a straight base line, the transverse or cross sections of the blade are substantially segments of serial hyper-bolas, each section being substan tially straight at the face, and having a hyperbolic curvature at the back. For most purposes, Hyperconic blades can advantageously be planar, that is with substantially a flat face and without helical twist, hence nominally without pitch; although the curved back produces an effective hydrodynamic pitch. Since this is also the .most economical and universal construction, it is the preferred general construction of the blades of the invention.

It is of course Well established that marin propellers in action produce thrust action by reason of an integrated positive hydraulic pressure on the blade driving face and an integrated negative pressure on the blade back; the latter being augmented by suitable transverse curvatures as in the present case. In typical blade forms of the prior art, the transverse blade sections have either a circular are or airfoil curvature across the back, and usually a straight, slightly curved, or lifted base line across the face. Also in conventional marine propellers the twisted blade face surface constitutes a helix. In the blade form of the invention, however, the transverse blade sections constitute segments of progressive hyperbolas hence each blade has a symmetric hyperbolic curvature across the back, and a straight or slightly convex base line across the face. The back surface is preferably that of a circular minor cut-out piece of a squat right circular cone of small slope, say having a slope of 5-l0. It can be shown that any secant plane parallel to the axis of a right circular cone gives a section comprising an intersecting hyperbola and a straight base line; that is, a segment of a hyperbola. A series of parallel secant planes yield sections of the same basic form as these blade sections. Hence, the back surfaces of a Hyperconic blade can be machine generated by turning a corresponding conical surface, and these surfaces are precisely faired during generation by turning, which makes them precisely smooth.

Moreover, in the case of fast running motorboat propellers as a typical case, the possibility of cavitation at the blade surfaces at and near the perimeter must be considered. It has been shown by reported experiments that cavitation can result from variations in the gradients of the blade surfaces; and also by shock waves set up at the entry edge of the blade. In the case of the Hyperconic blade, the entry angle is less and the curvature gradients smoother than for other blade forms of the prior art; hence this blade is superior from the stand-point of avoiding cavitation induced by shock waves across the blade; thereby deferring material cavitation to higher rotative speeds. Moreover it is well established that setting the propeller blades to optimum operating pitch gives smoother hydrodynamic performance and less cavitation, hence an adjustable pitch propeller having Hyperconic blades can produce maximum propulsion performance with minimum cavitation.

T he novel Hyperconic form of the present invention en ables propeller blades to be produced by a novel and highly advantageous production method with respect to economy and saving of material and labor, resulting in blades of high precision of form and surface.

Referring now to FIGS. IVa and lVb, Which illustrate schematically a practical set-up for machine generating the propelling surfaces of a Hyperconic blade of circular outline, it is assumed that a pair of blade blanks 20, 20", or suitable discs for making a blade pattern, are mounted securely in diametral arrangement on a lathe face plate 21, with mechanical means for positioning the discs with their diameters radially sloping from the center axis to the rim of the face plate. Such means may include pillow block 22, whose function is to elevate to a certain precalculated height the rim of the blade blanks at the center axis of the face plate. Upon rotation of the face plate while feeding a cutting tool (not shown) at a predetermined cross-angle or slope, say by uniformly advancing the cross-feed at the desired slope angle, or by uniform longitudinal advance of the carriage as in cutting threads, the back surface can be shaped by turning in a continuous cut to a high degree of precision and with perfectly faired curvatures over the whole blade surface. Likewise, a blade cast to almost exact size and shape, can be mounted on a face plat and finished turned in the same manner with a negligible waste of blade material as compared to ordinary propeller production practices. In the case of large propellers such as ship propellers, hydrorunners, etc., the blades could of course be turned in a boring machine, following the method described above.

Should the design of the propeller require blades with fiat driving faces, or slightly curved face surfaces in whole or in part, the same blade blanks 20, 20 can be mounted in similar manner on a face plate and the face surface of the blade shaped by turning as required. Referring now to FIG. V, which illustrates the method of turning face surfaces which are flat, or only slightly curved in whole or part, a pair of blade blanks can be mounted with their back surface against the face plate as shown, or slightly tilted as required. Also, the blade blanks can be located away from the axis, say by means of a spacer button 23, thereby to reduce the curvature along the contour arcs. If the outer edges of the blade blank are properly raised, so that the face surface is brought parallel to the face plate, and the cross-feed is quite parallel to the face plate, a perfectly fiat face surface can be turned to a high degree of precision. Whereas, in the case of blades with helical surfaces, even a nominally fiat blade surface can only be generated with great difficulty and never exactly.

Without further discussion, it should be evident to those skilled in the art that the invention provides novel propeller blade forms and teaches methods of propeller manufacture of ultimate simplicity and extraordinary precision and economy.

Referring again to FIG. I, for purposes of enabling the blades to be adjusted and set to a given pitch position, the universal adjustable pitch propeller of the invention is provided with special means for indicating visually the effective pitch of each blade. The preferred means comprises an arcuate series of graduated marks or scale 11 inscribed on the hub adjacent the rim of each blade socket and two single radial marks or indicators, designated by R and L respectively, inscribed on each blade boss 2b. The middle mark of the scale may be marked Mas shown to provide a median reference mark. The significance and use of these marks is based on the pitch angle of a propeller blade in relation to the pitch ratio of the propeller. It is demonstrated in standard texts on marine propellers that the relation of blade angle to effective propeller pitch accords with the equation:

where Q: the blade angle at the tip relative to the median plane of the propeller when the propeller pitch/ diameter ratio P/D. Since this relation applies to propellers of any size, the pitch angle of the individual blades can be set to obtain a given pitch ratio for the propeller taken as an entity according to the following table:

Table I Pitch Ratio Blade Angle (Q) 0.7 l2.6

l.l l9.3

Since the median pitch ratio of motor boat propellers is approximately unity, the middle scale mark, designated by the symbol M, can be located at the middle of the scale markings on the median axial plane of the associated blade socket as shown. Then with the pitch angle of the blade adjusted to +l7.7 with reference to the transverse plane of the blades a mark R, matching middle mark M, can be inscribed on the blade boss; thereby indicating that the blade is set to unity pitch ratio for a right turning propeller. When the blade is turned either way so as to move the mark R along the graduated scale, the blade pitch can be interpreted in terms of pitch ratio according to Table I.

Assuming next that the propeller is to rotate counterclockwise, that is to turn left hand in propeller parlance, the blade is turned about its axis to 17.7, and mark L inscribed to match middle scale mark M, thus indicating that the blade is set at unity pitch ratio for a left turning blade. As the blade is turned away from mark M, the blade setting can be interpreted in terms of propeller pitch ratio as before. Moreover, appropriate tables showing the proper blade settings for various boat speeds can be prepared and utilized to obtain optimum propeller performance in any given case; since the propeller performance at any pitch ratio and vessel speed is determinable from appropriate propeller tests, according to established practices of the art.

In summary, it will be observed that in typical cases according to the invention the propeller hub and propeller shaft are specified to have complementary tapered portions so that the hub can be readily mounted on any ordinary propeller shaft of matching size. The hub is also provided with equally spacedradial cylinderical blind bores constituting blade sockets. Each blade socket is provided with an internal circumferential groove, located intermediate its ends, which groove is adapted to seat a mating lock ring. The radial propeller blades are each provided with a circular boss adapted to fit any blade socket, whereby the blades are interchangeable and directly replaceable. Each blade boss is securely locked in its socket by means of an anchor disc retained in the bottom of its socket by a lock ring half-seated in the lock ring seating groove and plural lock screws mounted jointly in a blade boss and its associated anchor disc. When the lock screws are Wrenched tight, the blade boss and its anchor disc are locked solidly in the socket in any angular position to which they may be adjusted. Thus, the blades of the propeller of the invention can be set to any desired pitch angle.

The semiautomatic coupling and uncoupling device facilitates mounting and unmounting the propeller assembly on a shaft and thus adds a plus value. The novel Hyperconic blade reduces basic costs of production, promotes precision and propulsion efiiciency, eliminates cavitation, and adapts this propeller for either direction of rotation; whereby this novel and superior type of proeller achieves the capability of universal application.

Without further analysis, the teaching of the invention and various modes of putting the invention into practice will be evident from the foregoing. While the methods described herein, and the forms of apparatus for carrying these methods into effect, constitute preferred embodiments, it is to be understood that the invention is not limited to these and that changes may be made in either without departing from the scope of the invention which is defined in the appended claims.

I claim:

1. In an adjustable pitch marine propeller assembly, the coordinated combination comprising: a propeller shaft having a tapered end portion; a propeller hub having an axial bore tapered complementally to said tapered end portion and mounted solidly thereon, said hub having I equally spaced radial blind cylindrical bores constituting blade sockets; radial propeller blades each having a circular blade boss mating turnably in one of said sockets; means for immovably securing each blade boss in its socket comprising a coaxial circular anchor disc seated within said socket, and a circumferential lock ring seated within a circumferential groove in each said socket and externally accessible lock screw means mounted jointly in each said boss and its associated anchor discs whereby each boss can be locked in any angular position for purposes of pitch adjustment.

2. An adjustable pitch marine propeller assembly comprising the coordinated combination of: a propeller hub adapted for mounting coaxially on a complemental propeller shaft and having equally spaced radial blind cylindrical bores each constituting a blade socket; radial blades each having a cylindrical boss mounted turnably in one of said sockets; and lockable means for solidly securing each boss in its socket comprising a cylindrical anchor disc seated in the bottom of each socket, a lock ring halfseated in a circumferential groove in said socket so as to retain said anchor disc, and screw fastening means assembled jointly in said boss and said anchor disc, whereby each boss can be adjusted and locked in its socket in any angular position.

3. The combination of claim 2 in which the lockable means includes a plain open-ended retaining and locking ring half-seated in a groove in the inner circumference of each blade socket and half-seated in a concentric groove in the outer circumference of its mating discs and boss.

4. The combination of claim 2 in which the fastening means includes plural joining and lock screws mounted in a circular array jointly in each blade boss and its associated anchor disc.

5. The cornbination'specified in claim 2 and integral means for indicating visually the pitch angle of each individual blade.

6. In an adjustable pitch universal liquid propeller assembly, the coordinated combination of a central hub having radial blind blade sockets; radial blades each having a round boss turnably mounted in one of said blade sockets; means for securing each boss comprising an anchor disc seated in each said socket, and a securing lock ring fixedly positioned in each socket so as to secure said anchor disc in assembled position and externally turnable screw fastening means assembled jointly in each said blade boss and its anchor disc for securing and locking each blade boss and its anchor disc in any angular position.

7. An adjustable pitch marine propeller adapted for assembling to form a unitary propulsion device comprisiny the coordinated combination of: a propeller hub having an axial bore adapted for mounting on a complementary propeller shaft and having equally spaced radial cylindrical blind bores, each with an internal circumferential lock ring seating groove, constituting blade sockets; radial propeller blades each having a cylindrical boss at the inner end adapted to mate turnably in any of said blade sockets; an equal anchor disc for each blade boss adapted for mounting in the bottom of any blade socket; thrust bearing lock rings each adapted for assembling in any of said seating grooves so as to retain its associated anchor disc turnably in its socket; externally turnable demountable screw means mounted jointly in each boss and its anchor disc for fastening each of said blade bosses to its anchor disc and for locking said bosses and anchor discs in adjustable angular relation to said hub; and demountable screw means for securing said hub on its shaft assembled in said axial bore.

8. The combination of claim 7 and means for indicating visually the pitch angle of each of said propeller blades.

9. The combination specified in claim 7 with auxiliary semi-automatic means for coupling and uncoupling said hub on a complementary propeller shaft, said means including a jack screw element mountable on said shaft and turnable to move said hub coaxially along said shaft in reverse directions.

110. An adjustable pitch liquid impeller adapted for assembling to form a unitary operative device comprising the coordinated combination of: a hub element adapted for assembling solidly on a drive shaft and having equally spaced radial cylindrical blind bores, each with an internal circumferential ring-seating groove, constituting blade sockets; radial impeller blades each having a round boss at its inner end adapted to mate turnably in any of said blade sockets; an equal anchor disc adapted to fit turnably in the bottom of any blade socket; removable lock rings each adapted for assembling in any of said ring seating grooves so as to secure its associated anchor disc turnably in its socket; and externally turnable plural screw means mounted jointly in each boss and its anchor disc for fastening and locking each blade boss to its anchor disc and immovably in the hub element in any angular position.

11. A universal adjustable pitch liquid propeller characterized by the coordinated combination of: a hub member adapted for assemblying coaxially on a drive shaft and having equally spaced radial cylindrical blind bores, each with an internal circumferential ring seating groove, constituting blade sockets; radial blades each having a cylindrical boss mating turnably in a blade socket; and means for securing and locking each blade in its socket comprising an equal anchor disc seated turnably in the bottom of said socket, a removable lock ring half-seated in each ring seating groove so as to retain its associated anchor disc turnably in its socket, and externally turnable and removable plural screws mounted jointly in each said boss and its anchor disc for locking said anchor disc and blade boss immovably in said hub member in any angular position.

12. A universal adjustable pitch liquid propeller adapted for mounting on a complementary drive shaft comprising the coordinated combination of: a propeller hub having an axial bore adapted for mounting in mating relation on said drive shaft and having equally spaced radial blind bores constituting blade sockets; an anchor disc assembled turnably in the bottom of each blade socket; a removable retainer ring seated in a complementary circumferential groove in each blade socket for securing each said anchor disc in assembled position; individually adjustable and replaceable radial Hyperconic blades each having a circular boss at the hub end mated turnably in a blade socket; removable externally turnable screws mounted jointly in each boss and its anchor disc for securing said boss to its anchor disc and for locking both an adjustable angular position; and jack-screw means assembled in the axial bore of said hub for locking and unlocking said hub on said drive shaft.

13. The combination of claim 12 and means for indicating visually the pitch angle of said blades.

References Cited by the Examiner UNITED STATES PATENTS 985,491 2/ 1911 Andrade 29244 1,001,951 8/1911 Hawkins 159 2,283,956 5/1942 Smith 17 0159 2,347,282 4/1944 Roby 170173 2,382,535 8/1945 Bauer 170-173 X 2,485,809 10/1949 Biermann '170l73 2,908,335 10/1959 Petty 170173 3,132,698 5/1964 Lesher 170-173 MARK NEWMAN, Primary Examiner.

JULIUS E. WEST, Examiner.

W. E. BURNS, Assistant Examiner. 

1. IN AN ADJUSTABLE PITCH MARINE PROPELLER ASSEMBLY, THE COORDINATED COMBINATION COMPRISING: A PROPELLER SHAFT HAVING A TAPERED END PORTION; A PROPELLER HUB HAVING AN AXIAL BORE TAPERED COMPLEMENTALLY TO SAID TAPERED END PORTION AND MOUNTED SOLIDLY THEREON, SAID HUB HAVING EQUALLY SPACED RADIAL BLIND CYLINDRICAL BORES CONSTITUTING BLADE SOCKETS; RADIAL PROPELLER BLADES EACH HAVING A CIRCULAR BLADE BOSS MATING TURNABLY IN ONE OF SAID SOCKETS; MEANS FOR IMMOVABLY SECURNG EACH BLADE BOSS IN ITS SOCKET COMPRISING A COAXIAL CIRCULAR ANCHOR DISC SEATED WITHIN SAID SOCKET, AND A CIRCUMFERENTIAL LOCK RING SEATED 